1. Field of the Invention
The present invention relates generally to the reduction of drag on a vehicle moving through a fluid by injecting a polymer fluid into the boundary layer adjacent the nose portion of the vehicle, and deals more particularly with providing a unique nose portion for such a vehicle wherein a boundary layer fluid can be ejected either adjacent the nose at the center line of the vehicle, or can be ejected in the area of minimum pressure at the juncture between the nose of the vehicle and its cylindrical shell.
2. Description of the Prior Art
Polymer ejection systems for reducing the drag on a moving vehicle by ejecting a fluid at or near the area of minimum pressure in the nose portion of the vehicle are known. See for example Thompson, et al. U.S. Pat. Nos. 3,286,674, Hulsebos, et al. 3,392,693, Merrill 3,435,796, Fabula, et al. 4,186,679 and Nadolink 4,987,844. All of the above mentioned patents disclose the general concept of ejecting a polymer through ports which are spaced radially from the center line of the vehicle, and which are intended to introduce the fluid in the general area of minimum pressure where the surrounding fluid reaches its maximum velocity as the underwater vehicle is propelled through the fluid medium.
In the underwater test environment, so called buoyant test vehicles have been provided with polymer ejection ports in various locations including locations adjacent to the nose or forward end of the vehicle itself. In the testing environment, it has been necessary to replace the entire nose portion of such a buoyant test vehicle in order to test different configurations of ports, port sizes, slot shapes and to provide for testing of so called radial or forward end port ejection systems.